Studies on the relationships between biotin and the behaviour of B and T lymphocytes in the guinea-pig

Summary In biotin-deficient guinea-pigs the number of circulating neutrophils is increased; lymphocytes carrying B and T markers are decreased. Incubation with biotin increases significantly the number of lymphocytes carrying B and T markers, from biotin-deficient guinea-pigs; no increase was observed when the lymphocytes from normal guinea-pigs were incubated.     

Vasoactive intestinal peptide (VIP): specific receptors and adenylate cyclase activation in a human prolactin-secreting pituitary tumor]

Receptors for the Vasoactive Intestinal Peptide (VIP) were characterized in particles enriched in plasma membranes obtained from a human prolactin-secreting pituiatry tumor. Native VIP inhibited competitively the binding of 125I-VIP to the particles and stimulated cyclic AMP production; both these effects were observed at concentrations of VIP as low as 10(-11)-10(-10) M, which are compatible with VIP concentrations in the hypothalamopituitary portal blood.     

Daily melatonin injections inhibit short-day-induced testicular regression in hamsters

Summary Daily injections of melatonin were found to retard testicular regression in hamsters exposed to LD 10:14, if the injections occurred in the morning (i.e., 0.5 h after lights on), but not if they occurred in the afternoon (i.e., 6 h after lights on). These results indicate that appropriately timed injections of melatonin can at least partially block the inhibitory effects of short days on gonadal activity in the photoperiodic hamster.We wish to thank Susan Losee and Susan Stice for excellent technical assistance and Gary Ellis for his comments. This investigation was supported by NIH grants HD-09885, HD 12622 and Research Career Development Award HD-00249 (F. W. T.) from the National Institute of Child Health and Human Development.